The invention is related to Internet protocol (IP) based telephony communications systems. More specifically, the invention is related to IP based private branch exchange systems and service providers.
Traditionally, a professional services business that employed multiple individuals would provide each individual with a telephone at their respective desk. However, in light of the fact that it is unusual in most businesses for all the employees to be conducting telephone calls at the same time, the business would not have a separate telephone line connected to each telephone. Instead, the business would acquire a lesser number of external telephone lines, and those external telephone lines would be coupled to a special switching unit located within the business. Each of the employee telephones also would be coupled to the switching unit. The switching unit allows any employee telephone to be connected to any of the external telephone lines. The switching unit also allows a receptionist to answer each incoming telephone call, and then connect that call to the appropriate employee telephone. Such a switching system is commonly known as a private branch exchange (PBX) system.
The heart of a traditional the private branch exchange system is the switching unit to which the external lines and the employee telephones are connected. Unfortunately, such switching systems are relatively expensive. In addition, if a growing business purchases a first switching system with a certain capacity, it is common for the business to outgrow the first switching system. This usually means that the business must purchase a new, larger capacity switching system, and then discard or resell the first switching system.
With the rise in Internet protocol (IP) telephony systems, some IP telephony service providers have begun to offer telephony services that mimic a traditional private branch exchange system. Instead of all employee telephones being connected to a central switching unit located at the business, each employee is provided with an IP telephony device which is coupled to the Internet. When an employee's IP telephony device is first coupled to the Internet, it registers with the private branch exchange service provider, providing an Internet address at which it can be reached. Thereafter, incoming telephone calls can be directed to the employee telephone by the private branch exchange service provider via the Internet. Likewise, if an employee wishes to place an outgoing telephone call, the outgoing call is setup through the private branch exchange service provider via the Internet.
An IP based private branch exchange service has several advantages over a traditional switching unit based private branch exchange system. First, because employee IP telephony devices need only be connected to the Internet, the employees can be located virtually anywhere they can obtain access to the Internet. There is no longer a need for an employee telephony device to be hard wired to a PBX switching unit.
In addition, an IP based private branch exchange service provider can allow a business to scale upward and downward, in terms of the number of users, with few limits. Thus, a business is no longer locked into a PBX switching unit with a fixed capacity. There is also no longer a need for a business to purchase or lease the expensive switching unit associated with a PBX system.
On the other hand, an IP based private branch exchange service also has certain inherent disadvantages. Chief among them is that Internet connectivity is required to receive incoming calls and place outgoing calls. Even if a first employee of a business wishes to place an intra-office call to a second employee of the same business, in the same building, it is necessary for the call to be routed through the IP based private branch exchange service, which is only reachable via the Internet. This is true even when the first and second employees' IP telephony devices are connected to the same local area network that provides access to the Internet.